Technical Abstract:
The studies reported here are part of the USDA-ARS Areawide Pest Management Program for Alternatives to Methyl Bromide South Atlantic Area and involve a cooperative effort between Florida in-ground ornamental producers, fumigant industry representatives, and researchers from the USDA, ARS and University of Florida. Fumigation with methyl bromide:chloropicrin (98:2 or 89:11) has been the standard method for production of high quality cut flowers, tubers, and bulbs. This material has allowed these industries to grow a large number of highly diverse crops and has addressed the need for control of multiple pests as well as for the control of propagules of previous crops as rogues in following seasons. Selection of species and varieties to produce is highly marketdriven, and methyl bromide has allowed for the flexibility needed to make rapid decisions on planting schedules. The studies reported here were designed to test the efficacy of the most readily available chemical alternatives, methyl iodide:chloropicrin (now registered as MIDAS®, Arysta LifeScience Corp.) and dimethyl disulfide:chloropicrin (EUP available as Paladin™, United Phosphorous, Inc. King of Prussia, PA), applied with standard equipment utilized by commercial applicators with currently available plastic films and application technology. Studies were designed as replicated, randomized complete blocks with split plots to accommodate multiple cultivars. Trials are on-going and conducted over multiple seasons. Two locations were selected for these trials. The first, in Hobe Sound, FL, included a methyl bromide standard application of 400lb/A (98:2), MIDAS® (50:50) at 300 lb/A, and Paladin™ (79:21) at 74 gal/A. The trial consisted of three replications per treatment with each main plot replicate representing a full lateral (26’ x 110’). Plots were split to contain two rows each of delphinium cultivars ‘Belladonna’ and ‘Bellamosum’. All materials were applied on August 8, 2007 by Hendrix and Dail using standard broadcast application equipment and 1mil clear plastic mulch. At the second site, located in Zolfo Springs, FL, the producer initiated a trial prior to the formal start of the Areawide project in which a standard application of methyl bromide (360 lb/A of 89.5:10.5 methyl bromide:chloropicrin) was compared to MIDAS® (50:50 at 300 lb/A) and Paladin™, (79:21 at 74 gal/A). All materials were applied using standard broadcast tarping procedures (1 mil) and had a previous deep shank application of Telone C-35 at 12-14”. The Telone application was made by the grower with equipment provided by Hendrix and Dail. Application of the methyl bromide, MIDAS®, and Paladin™, was made by Hendrix and Dail. Each treatment was replicated four times and each replicate consisted of a full lateral with size ranging from 0.23 to 0.28 A per lateral. The trial was planted to the caladium cultivar White Queen. The Areawide trial initiated at the Zolfo Springs site included two formulations of MIDAS® (98:2 at 100 lb/A and 50:50 at 160 lb/A), Paladin™, (79:21 at 60 gal/A), and methyl bromide:chloropicrin (98:2 at 180 lb/A) all applied under high barrier, Blockade® plastic mulch (Pliant Corp., Chippewa Falls, WI) using raised beds. All test material applications were preceded by a deep shank application of Telone C-35 as previously described. Each treatment was replicated four times with a full lateral representing a main plot treatment. Each lateral was split into four sub-plots (one 600ft row each) and these were planted to four different caladium cultivars. Nematode and fungal populations at each field site were assessed prior to fumigation, two-to-five days following tarp removal, at mid-season of the crop, and at the initiation of harvest. Ten soil cores were taken in each plot using a 2.5-cm-diam soil probe. These were combined, and a 100-cm3 subsample was used to